Not Using Dispose or Using() in Entity Framework

Question

I was writing a web app and learning entity framework along the way. I am curios if I have done something wrong though. I haven't been using dispose or using statements when querying.

Example of a Repository of mine:

public User GetUserById(int sessionId)
{
    var user = (from u in db.Users where u.Id == sessionId select u).SingleOrDefault();
    return user;
}

My User table I selected from would have foreign keys which would be associated with other tables. The cool thing, or so I thought, about entity is that I could return the entire User object (built by entity) which then would allow me to do something like this User.MyOtherTable.SomeColumn in my controller.

The problem is I relied on this and went about my merry way in my controller of grabbing the user information as well as utilizing information from the other table. I am now realizing that if I close that connection like the code below:

public User GetUserById(int sessionId)
{   using(db)
    {
    var user = (from u in db.Users where u.Id == sessionId select u).SingleOrDefault();
    return user;
    }
}

My controller no long has access to User.MyOtherTable.SomeColumn as this will be null. My true question is how important is it for me use dispose in my entity application?

Answer 1

I would strongly recommend that you use using statements, and also that you stop relying on lazy-loading.

Instead of selecting User objects with lazy-load properties, work out the full data you need and project that to a Model class, e.g.

public class UserWithOtherStuffModel
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string OtherStuff { get; set; }
}

Then in your method:

public UserWithOtherStuffModel GetUserById(int sessionId)
{
    using(db)
    {
        var user = (from u in db.Users 
            where u.Id == sessionId 
            select new UserWithOtherStuffModel{
                Id = u.Id,
                Name = u.Name,
                OtherStuff = u.MyOtherTable.SomeColumn
            }).SingleOrDefault();
        return user;
    }
}

Not only does this mean you limit the number of database calls, but you have a data contract that isn't tied to your database model. If you move that column, you simply update the query to point to the new spot/name, the view can remain unchanged.